Wind and nebula of the M33 variable GR290 (WR/LBV)

Context: GR290 (M33/V532=Romano's Star) is a suspected post-LBV star located in M33 galaxy that shows a rare Wolf-Rayet spectrum during its minimum light phase. In spite of many studies, its atmospheric structure, its circumstellar environment and its place in the general context of massive stars evolution is poorly known. Aims: Detailed study of its wind and mass loss, and study of the circumstellar environment associated to the star. Methods: Long-slit spectra of GR290 were obtained during its present minimum luminosity phase with the GTC together with contemporaneous BVRI photometry. The data were compared with non-LTE model atmosphere synthetic spectra computed with CMFGEN and with CLOUDY models for ionized interstellar medium regions. Results: The current $m_V=18.8$ mag, is the faintest at which this source has ever been observed. The non-LTE models indicate effective temperature $T_{eff}$=27-30 kK at radius $R_{2/3}$=27-21 Rsun and mass loss rate $\dot{M}=1.5\times10^{-5}$ Msun yr$^{-1}$. The terminal wind speed $V_\infty$=620 ${\rm km~s^{-1}}$ is faster than ever before recorded while the current luminosity $L_*=(3.1-3.7)\times 10^5$ Lsun is the lowest ever deduced. It is overabundant in He and N and underabundant in C and O. It is surrounded by an unresolved compact HII region with dimensions $\leq$4 pc, from where H-Balmer, HeI lines and [OIII] and [NII] are detected. In addition, we find emission from a more extended interstellar medium (ISM) region which appears to be asymmetric, with a larger extent to the East (16-40 pc) than to the West. Conclusions: In the present long lasting visual minimum, GR290 is in a lower bolometric luminosity state with higher mass loss rate. The nearby nebular emission seems to suggest that the star has undergone significant mass loss over the past $10^4-10^5$ years and is nearing the end stages of its evolution.Comment: submitted to A&A, 12 pages, 9 figures, 7 table

Dark polariton-solitons in semiconductor microcavities

We report the existence, symmetry breaking and other instabilities of dark polariton-solitons in semiconductor microcavities operating in the strong coupling regime. These half-light half-matter solitons are potential candidates for applications in all-optical signal processing. Their excitation time and required pump powers are a few orders of magnitude less than those of their weakly coupled light-only counterparts.Comment: submitted to PR

Bounds on positive interior transmission eigenvalues

The paper contains lower bounds on the counting function of the positive eigenvalues of the interior transmission problem when the latter is elliptic. In particular, these bounds justify the existence of an infinite set of interior transmission eigenvalues and provide asymptotic estimates from above on the counting function for the large values of the wave number. They also lead to certain important upper estimates on the first few interior transmission eigenvalues. We consider the classical transmission problem as well as the case when the inhomogeneous medium contains an obstacle.Comment: We corrected inaccuracies cost by the wrong sign in the Green formula (17). In particular, the sign in the definition of \sigma was change

Disturbances of electron density in the high latitude upper (F-region) ionosphere induced by X-mode HF pump waves from EISCAT UHF radar observations

The paper presents experimental results concerning disturbances of electron density in the high latitude ionosphere F-region, induced by powerfulHF radio waves (pump waves) with extraordinary (X-mode) polarization. The experiments were carried out at the EISCAT/Heating facility at Tromsø, Norway. The EISCAT UHF incoherent scatter radar (ISR), running at 930 MHz, co-located with a heating facility, was used to detect the disturbances of electron density. In the course of the experiments, the X-mode HF pump waves radiated into the F-region towards the magnetic zenith at different pump frequencies and ratios of the pump frequency to the critical frequency of the F2 layer.The effective radiated power was ERP = 360–820 MW. An increase in electron densities was found in a wide altitude range, giving rise to field-aligned ducts with enhanced electron density. The features and behavior of the ducts were investigated. It was revealed that the ducts are formed under quiet background geophysical conditions in a wide altitude range up to the upper altitude limit of EISCAT ISR measurements, when the pump frequencies were both below and above the critical frequency of the F2 layer (fH ≤ foF2 or fH > foF2). A plausible formation mechanism of the ducts is discussed.Представлены результаты экспериментальных исследований возмущений электронной концентрацииNe в высокоширотной F-области ионосферы, вызванные воздействием мощных КВ-радиоволн необыкновенной (Х-мода) поляризации. Эксперименты выполнялись на КВ нагревном стенде EISCAT/ Heating в г. Тромсё, Норвегия при эффективной мощности излучения 360–820 МВт. В качестве средства диагностики возмущений Ne использовался EISCAT радар некогерентного рассеяния радиоволн (НР) на частоте 930 МГц, пространственно совмещенный с КВ нагревным стендом. Обнаружено возрастание Ne в широком диапазоне высот, которое формирует каналы повышенной электронной плотности, вытянутые вдоль магнитного поля Земли. Исследованы характеристики и условия создания каналов. Обсуждается возможный механизм формирования каналов Ne при Х-нагреве высокоширотной F-области ионосферы

Heat-kernel coefficients for oblique boundary conditions

We calculate the heat-kernel coefficients, up to $a_2$, for a U(1) bundle on the 4-Ball for boundary conditions which are such that the normal derivative of the field at the boundary is related to a first-order operator in boundary derivatives acting on the field. The results are used to place restrictions on the general forms of the coefficients. In the specific case considered, there can be a breakdown of ellipticity.Comment: 9 pages, JyTeX. One reference added and minor corrections mad

Семейство электронных стрелковых тренажёров «СТрИж»: уровни реализации и структура свободного программного обеспечения

Development of rifle electronic simulators (i.e. for hand weapons and not using ammunition) is an important task, since the production of any type of small arms according to regulatory documents also requires the production of a simulator to instill aiming and firing skills. A family of electronic shooting simulators "STrIzh" of four levels of implementation: initial, basic, professional and special is described. Structural diagrams of different configurations are given, functional purpose and capabilities of each level of simulators are shown. The initial level allows independent assemble the simulator from publicly available elements (laptop, webcam, weapon layouts, IR LEDs), which can contribute to widespread use both in schools and at home, but is low in accuracy and manufacturabili (requires daily calibration). The basic level also allows independent assemble the simulator, and less publicly available elements (laptop, projector, mockup weapons, laser emitters, FHD camera), which allows to be used both in schools and in DOSAAF structures, and has acceptable accuracy and manufacturability (a weekly calibration is enough, but assembling a mock-up weapon with laser emitters requires adjustments). It is recommended to limit the special level to virtual reality simulators, including a helmet with a smartphone and a mockup of a weapon with its smartphone which also contributes to its public availability and widespread use. The simulator software algorithm should fully support all implementation levels with different configurations and include a multimedia shooting training system. Mathematical models of external ballistics of thrown equipment for Kalashnikov assault rifle, Makarov pistol, hand-held anti-tank grenade launcher 7 products are described in detail, taking into account changes in atmospheric factors (temperature, air pressure, wind force) and dispersion of various types of ammunition. The above review of rifle simulators and their experience revealed the main trends of improvement – use of virtual reality and training not only direct shooting skills, but also training in the eligibility of the use of weapons, safe handling of them and even tactical interaction in the group. Разработка стрелковых электронных тренажёров (т. е. для ручного оружия и не использующих боеприпасы) является важной задачей, т. к. производство любого вида стрелкового вооружения, согласно нормативным документам, требует и производства тренажёра для привития навыков прицеливания и стрельбы. Описано семейство электронных стрелковых тренажёров «СТрИж» четырёх уровней реализации: начального, базового, профессионального и специального. Приведены структурные схемы различных конфигураций, показано функциональное назначение и возможности каждого из уровней тренажёров. Начальный уровень позволяет самостоятельно собирать тренажёр из общедоступных элементов (ноутбук, веб-камера, макеты оружия, ИК-светодиоды), что может способствовать широкому применению как в школах, так и дома, но отличается низкой точностью и технологичностью (требует ежедневной тарировки). Базовый уровень также позволяет самостоятельно собирать тренажёр, но уже из менее общедоступных элементов (ноутбук, проектор, макет оружия, лазерные излучатели, FHD-камера), что позволяет применять его как в школах, так и в структурах ДОСААФ, имеет приемлемую точность и технологичность (достаточно еженедельной тарировки, но сборка макета оружия с лазерными излучателями требует юстировки). Специальный уровень рекомендуется ограничить тренажёрами виртуальной реальности, включающие шлем со смартфоном и макет оружия со своим смартфоном, что также способствует его общедоступности и широкому использованию. Алгоритм работы программного обеспечения тренажёра должен полностью поддерживать все уровни реализации с различными конфигурациями и включать мультимедийную систему обучения стрельбе. Подробно описаны математические модели внешней баллистики метаемого снаряжения для автомата Калашникова, пистолета Макарова, ручного противотанкового гранатомёта 7, учитывающие изменение атмосферных факторов (температуры, давления воздуха, силы ветра) и рассеивание различных типов боеприпасов. Приведённый обзор стрелковых тренажёров и опыта их эксплуатации выявил основные тенденции совершенствования – использование виртуальной реальности и тренировка не только навыков непосредственно стрельбы, но и обучение правомочности применения оружия, безопасного обращения с ним и даже тактическому взаимодействию в группе.

The relationship between cellular and calcium responses of Aspergillus awamori to external influences

The cellular and Ca2+ responses to physiological stimuli of different nature were studied in the experiments with the strain Aspergillus awamori 66A containing recombinant aequorin, a Ca2+-dependent photosensitive protein. The relationship between the cellular response registered by changes in the development of the mycelial fungus (colony growth, hyphal branching, and the rate of spore formation) and the level and duration of calcium flares in the cytosol was assessed. The physical or chemical stimuli (mechanical effect, osmotic shock) inducing short-time calcium flares in the cytosol did not influence significantly the development of A. awamori grown in liquid or on solid nutrient media. The action on the 24-h A. awamori culture of the Ca2+-selective ionophore (A23187) inducing long-term changes in calcium homeostasis caused disorders in the fungus development and morphology (hyperbranching of mycelial hyphae, formation of spherical cells, and inhibition of colony growth and spore formation). Thus, it was established that the development of cellular response in the micromycete correlated with the duration of the calcium flare in the cytosol. © 2010 Pleiades Publishing, Ltd